3 reasons to use UV-C disinfection
UV-C light damages the genetic material of microbes so that they can no longer multiply. Germicidal lamps have been used in healthcare for decades. Here are three reasons why organisations use them, and what is worth knowing before you buy.
1. No chemicals and no residue
UV-C is ultraviolet radiation with a wavelength of about 200–280 nm. A standard germicidal lamp emits at 254 nm. The radiation damages the DNA or RNA of bacteria and viruses, so they can no longer multiply or infect. Nothing is left behind on surfaces or in the air. After a device with an ozone-free lamp, the room can be used straight away.
2. Air and surfaces that are not wiped every day
Infections also spread through the air, and UV-C reaches places that cleaning does not cover every day. There are two main types of device:
- A recirculator draws air through a closed chamber that the radiation cannot leave. It can work while people are present, for example in a classroom, waiting area or consulting room.
- A direct UV-C lamp irradiates the air and surfaces directly, so it is used in an empty room only: at night, between shifts or after a sick visitor.
3. Everyday hygiene and infection control
In schools, kindergartens, family medicine centres and veterinary clinics, UV-C is one part of infection control alongside cleaning and airing. A recirculator runs quietly in the background during the working day, and a direct UV-C lamp cleans the room when nobody is there.
What to keep in mind
- The result depends on the dose. The dose is irradiance multiplied by time. It drops quickly with distance, and UV-C does not work in shadow. Bacteria need a higher dose than many viruses, and spores a higher one still.
- UV-C does not replace cleaning. Dust and dirt shield microbes, so surfaces need to be clean.
- A recirculator only cleans the air that passes through its chamber. The result in the room depends on how many times an hour the device passes the room’s air through. That is why we choose the device by room size.
- Direct UV-C is harmful to the eyes and skin. No people or animals may be in the room. A timer, motion sensor or door switch helps.
- Ozone: indoors, choose a device with an ozone-free lamp.
- Lamps age. A lamp is replaced after the hours stated by the manufacturer, even if it still glows.
The Health Board (Terviseamet) advises using a device according to the manufacturer’s instructions, choosing one whose manual describes safety thoroughly, and being careful with advertising that promises miracle results: Health Board recommendations on choosing and using UV devices (in Estonian).
How to choose
If people are in the room during working hours, choose a recirculator. If the room can be left empty, a direct UV-C lamp fits. Every device states whether people can stay in the room or whether it works in an empty room only.
If you are not sure what fits, ask for advice: we work out from the room size and use how many devices you need and which ones.